The invention relates to the general field of aviation. In particular, the invention relates to detecting ingestion of water or hail by an aeroengine gas turbine.
An aeroengine gas turbine typically comprises a combustion chamber, with the combustion gases from the combustion chamber driving a high-pressure (HP) turbine and a low-pressure (LP) turbine. The HP turbine is coupled by a shaft to an HP compressor feeding the combustion chamber with compressed air, while the LP turbine is coupled by another shaft to a fan at the inlet of the engine.
The fan and the compressor absorb the air needed for proper operation of the engine, but depending on atmospheric conditions, they may also ingest water or hail, e.g. when the aircraft encounters a storm or passes through a cloud bank. The water and hail as absorbed in this way can disturb the operation of the engine.
When operating at full throttle, the compressor can generally raise the temperature of the air sufficiently for the water that is ingested to be vaporized and raised to a temperature that is high enough to avoid leading to flame-out of the combustion chamber. In contrast, if the engine is at idling speed, e.g. during a descent trajectory, on approach, when landing, the water can reach the combustion chamber leading to one or more burners flaming-out or even to the entire combustion chamber flaming-out and the engine stopping.
It is therefore desirable to detect the ingestion of water or hail and to adapt the operation of the engine accordingly.
For this purpose, document FR 2 681 377 proposes detecting the ingestion of water as a function of a difference between the temperature T2 of the air at the inlet to the compressor and T3 at the outlet from the compressor. Furthermore, such detection may be confirmed by estimating the efficiency of combustion.
A drawback of that solution is that it requires the characteristics of the engine to be determined empirically. Furthermore, depending on circumstances, it is possible that ingestion of water goes undetected. The calculated temperature difference is not suitable for detecting the ingestion of water under all circumstances.
Document U.S. Pat. No. 5,471,831 also proposes detecting the ingestion of water from the temperature of the air at the inlet and the outlet of the compressor, and from the pressure in the combustion chamber. In that document likewise, and depending on circumstances, it is possible for the ingestion of water to go undetected. Pressure variations in the combustion chamber are rather small to be able to draw clear conclusions therefrom.
There thus exists the need to detect ingestion of water or hail in a manner that is robust, effective, and fast.